1. Technical Field
The present invention relates to a honeycomb structure body. More particularly, the present invention relates to a honeycomb structure body having joining material layers of a stress relaxing function and joining strength equivalent to those of joining material layers of a conventional honeycomb structure body, and having an excellent heat shock resistance.
2. Description of Related Art
As a collecting filter for an exhaust gas, for example, a diesel particulate filter (DPF) to trap and remove a particulate matter (particulates) included in an exhaust gas from a diesel engine or the like, a honeycomb structure body has broadly been used.
Such a honeycomb structure body has, for example, a structure in which a plurality of cells formed by porous partition walls made of silicon carbide (SiC) or the like to become through channels of a fluid are arranged in parallel with one another in a central axis direction. Moreover, end portions of the adjacent cells are plugged alternately (in a checkered pattern). That is, in one of the cells, one end portion is open, and the other end portion is plugged. Furthermore, in the other cell adjacent to the one cell, one end portion is plugged, and the other end portion is open.
According to such a structure, the exhaust gas can be purified as follows. First, the exhaust gas is allowed to flow into a predetermined cell (an inflow cell) from the one end portion of the cell. In this case, the above exhaust gas passes through the porous partition wall. Moreover, when the exhaust gas passes through the partition wall, the particulate matter (the particulates) in the exhaust gas is trapped by the partition wall. Therefore, the purified exhaust gas is discharged through the cell (an outflow cell) adjacent to the inflow cell.
For the purpose of using such a honeycomb structure body (the filter) continuously for a long period of time, it is necessary to periodically subject the filter to a regeneration treatment. That is, in the filter, the particulates are deposited with an elapse of time. Therefore, for the purpose of returning a filter performance to an initial state, i.e., decreasing a pressure loss which has increased due to the particulates, it is necessary to burn and remove the particulates deposited in the filter. However, at the regeneration of this filter, a large heat stress (hereinafter referred to simply as “the stress” sometimes) takes place in the filter, and hence this heat stress disadvantageously generates defects such as cracks or breakdowns in the honeycomb structure body. Consequently, to solve the above problem due to this heat stress (in other words, to meet a demand for enhancement of a heat shock resistance), there have been suggested honeycomb structure bodies having a divided structure in which a plurality of honeycomb segments are integrally joined by a joining material layer (see Patent Documents 1 to 4). The above honeycomb structure bodies have such a divided structure, and are therefore provided with a function of dissipating and relaxing the heat stress. Moreover, according to such honeycomb structure bodies, the heat shock resistance can be improved to a certain degree.